title: Effects of hyperoxia on the permeability of 16HBE14o- cell monolayers--the protective role of antioxidant vitamins E and C.
abstract: The use of hyperoxia for critically ill patients is associated with adverse impacts resulting in lung injury accompanied by inflammation. The aim of this study was to evaluate aspects of mechanisms that contribute to hyperoxia-induced disruption of the epithelial permeability barrier, and also the protective effects of the antioxidants α-tocopherol and ascorbate. 16HBE14o- cells were cultured as monolayers at an air-liquid interface for 6 days, after which transepithelial electrical resistance reached 251.2 ± 4.1 Ω.cm(2) (mean ± standard error of the mean). They were then exposed for 24 h to normoxia (21% O2, 5% CO2), hyperoxia (95% O2, 5% CO2), hyperoxia with 10(-7) M α-tocopherol, hyperoxia with 10(-7) M ascorbate, hyperoxia with 10(-6) M ascorbate, and hyperoxia with a combination of α-tocopherol and ascorbate (10(-7) M and 10(-6) M, respectively). Significant reductions (P < 0.05) in transepithelial electrical resistance seen after hyperoxia (with or without antioxidants) were associated with reductions in the levels of zona occludens-1 (ZO-1) observed by immunohistochemistry, and downregulation of ZO-1 expression (P < 0.01) as compared with normoxia. In contrast, the expression levels of interleukin (IL)-8, IL-6 and tumour necrosis factor-α (TNF-α) were increased after hyperoxia (P < 0.01), and marked increases in the levels of these cytokines (ELISA) were seen in the medium (P < 0.001) as compared with normoxia. The antioxidant vitamins E and C had a partial protective effect against the hyperoxia-induced reduction in ZO-1 levels and the increase in levels of the proinflammatory cytokines IL-8, IL-6, and TNF-α. In conclusion, hyperoxia-induced epithelial disruption is associated with tight junction weakening, and induction of a proinflammatory environment.
authors.affiliation: School of Biomedical and Biological Sciences, University of Plymouth, UK.
authors.forename: Hanady S
authors.initials: HS
authors.lastname: Al-Shmgani
authors.forename: Roy M
authors.initials: RM
authors.lastname: Moate
authors.forename: Peter D
authors.initials: PD
authors.lastname: Macnaughton
authors.forename: J Robert
authors.initials: JR
authors.lastname: Sneyd
authors.forename: A John
authors.initials: AJ
authors.lastname: Moody
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D017097:Electric Impedance; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D018496:Hyperoxia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D015850:Interleukin-6 / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D020545:Respiratory Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D014810:Vitamin E / Q000494:pharmacology*; D062826:Zonula Occludens-1 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
chemical_list: D000975:Antioxidants; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; C569042:TJP1 protein, human; D014409:Tumor Necrosis Factor-alpha; D062826:Zonula Occludens-1 Protein; D014810:Vitamin E; D001205:Ascorbic Acid; D010100:Oxygen
keywords: immunohistochemistry; proinflammatory cytokines; tight junctions; transepithelial resistance; zona occludens-1